Moved from "FUEL" forum

pinging is straight foward.. too much timing for you engine. first, disconnect the vacuum advance temporarly and see if it still pings.
back off the initial timing 5 degrees, reconnect the vac.adv.(to a PORTED vac.source) and see if it still pings. if it does, you either have:

A. Still way to much initial advance (should be no more the 15 degrees) or
B. Too much mechanical advance coming in too soon.

to find how much mech.adv. you have, you'll need a dial back timing light, or timing tape on your dampner.
should be no more then 38degrees(vac. disconnected) total at anything under 3000rpm. But I assume that you still have the stock
springs in the dizzy, so my bet is way to much advance. plus a rich mixture is sometimes and indication of too much timing.

as for your engine reving up when you give it slight choke, its designed to do that.

finally (i have to ask) are you positive your hearing pinging, and not an exhaust leak?

try those things. keep us posted.